a, \(\frac{34}{13}-\frac{19}{28}-\frac{3}{31}=>\left(\frac{34}{13}-\frac{3}{31}\right)-\frac{19}{28}\)

= \(1-\frac{19}{28}=\frac{9}{28}\)

b, \(b,\frac{7}{3}-\left(\frac{11}{5}+\frac{4}{5}\right)\)

= \(\frac{7}{3}-3=>\frac{7}{3}-\frac{9}{3}=\frac{-2}{3}\)

c, \(\frac{18}{13}+\frac{55}{46}-\frac{5}{13}=\left(\frac{18}{13}-\frac{5}{13}\right)+\frac{55}{46}\)

= \(1+\frac{55}{46}=\frac{46}{46}+\frac{55}{46}=\frac{101}{46}\)

đúng nha 100%

a) = 34/31 - 3/31 - 19/28 = 1 - 19/28 = 9/28

b) 18/13 - 5/13 + 55/46 = 1 + 55/46 = 101/46

c) 7/3 - 4/3 + 11/5 = 1 + 11/5 = 16/5

d) ( 27/25 - 2/25 ) - ( 5/9 + 4/9 ) = 1 - 1 = 0

e) 2,125 + 43/8 + 7,15 + 137/20  + 7,5 

= 2,125 + 5,375 + 7,15 + 6,85 + 7,5 

= 7,5 + 14 + 7,5

= 7,5 + 7,5 + 14

= 15 + 14

= 29

a) Nhóm 34/31 với 3/31

b) Nhóm 18/13 với 5/13

c) Nhóm 7/3 với 4/3

d) Phá ngoặc ra rồi tính

e) Bêến đổi đều thành phân số rồi tính

a) 34/31 - 19/28 - 3/31

(34/31 - 3/31) - 19/28

=           1         - 19/28

=9/28 (rút gọn tự tính)

b) 18/13 + 55/46 - 5/13

=(18/13 - 5/13) + 55/46

=          1         + 55/46

= 101/46 (rút gọn tự tính)

c) 7/3 + 11/5 - 4/3

=(7/3 - 4/3) + 11/5

=       1       + 11/5

= 16/5 (rút gọn tự tính)

d) (27/25 - 4/9) - (2/25 - 5/9)

=(27/25 - 2/25) - (5/9 - 4/9)

=          1         -      1/9

=8/9 (rút gọn tự tính)

e) 2.125 + 5 và 3/8 + 7.15 + 6 và 17/20 + 7.5

=2.125 + 5.375 + 7.15 + 6.85 + 7.5

= (2.125 + 5.375 + 7.5) + (7.15 + 6.85)

=                15              +        14

=                                 19

a. \(\left(\frac{34}{31}-\frac{3}{31}\right)-\frac{19}{28}=1-\frac{19}{28}=\frac{1}{7}\)

Làm tương tự ở các câu sau thôi bạn

yutyugubhujyikiu

Trả lời

b)(1/3+12/67+13/41)-(79/67-28/41)

=1/3+12/67+13/41-79/67+28/41

=1/3+(12/67-79/67)+(13/41+28/41)

=1/3+(-67/67)+41/41

=1/3+(-1)+1

=1/3+0

=1/3.

c)38/45-(8/45-17/51-3/11)

=38/45-8/45+17/51+3/11

=30/45+1/3+3/11

=2/3+1/3+3/11

=3/3+3/11

=1+3/11

=1 3/11.

d)(17/28+18/29-19/30-30/31).(-5/12+1/4+1/6)

=(17/28+18/29+19/30+30/31).(-5+3+2/12)

=(17/28+18/29+19/30+30/31).0

=0.

\(A=49\frac{8}{23}-\left(5\frac{7}{32}+14\frac{8}{23}\right)\)

\(A=49\frac{8}{23}-5\frac{7}{32}+14\frac{8}{23}\)

\(A= \left(49\frac{8}{23}-14\frac{8}{23}\right)-5\frac{7}{32}\)

\(A=\left[\left(49-14\right)-\left(\frac{8}{23}-\frac{8}{23}\right)\right]-5\frac{7}{32}\)

\(A=\left[35-0\right]-5\frac{7}{32}\)

\(A=35-5\frac{7}{32}\)

\(A=\frac{953}{32}\)

\(B=71\frac{38}{45}-\left(43\frac{38}{45}-1\frac{17}{57}\right)\)

\(B=71\frac{38}{45}-\frac{36377}{855}\)

\(B=\frac{1670}{57}\)

\(C=\left(19\frac{5}{8}:\frac{7}{12}-13\frac{1}{4}:\frac{7}{12}\right):\frac{4}{5}\)

\(C=\left[\left(19\frac{5}{8}-13\frac{1}{4}\right):\frac{7}{12}\right]:\frac{4}{5}\)

\(C=\left[\frac{51}{8}:\frac{7}{12}\right]:\frac{4}{5}\)

\(C=\frac{153}{14}:\frac{4}{5}\)

\(C=\frac{765}{56}\)

\(D=\left[\left(\frac{10}{15}-\frac{2}{3}\right):\frac{1}{7}\right]\cdot0,15-\frac{1}{4}\)

\(D=\left[0:\frac{1}{7}\right]\cdot\frac{3}{20}-\frac{1}{4}\)

\(D=0\cdot\frac{3}{20}-\frac{1}{4}\)

\(D=0-\frac{1}{4}\)

\(D=-\frac{1}{4}\)

\(E=\frac{13}{30}+\frac{28}{45}\cdot2\frac{1}{2}-\left[\left(\frac{1}{2}+\frac{1}{3}\right):\frac{53}{90}\right]:\frac{50}{53}\)

\(E=\frac{13}{30}+\frac{28}{45}\cdot\frac{5}{2}-\left[\frac{5}{6}:\frac{53}{90}\right]:\frac{50}{53}\)

\(E=\frac{13}{30}+\frac{28}{45}\cdot\frac{5}{2}-\frac{75}{53}:\frac{50}{53}\)

\(E=\frac{13}{30}+\frac{14}{9}-\frac{3}{2}\)

\(\)\(E=\frac{22}{45}\)

CHUC BAN HOC TOT >.<

a, 1 - 7x = 3x - 4

=> -7x - 3x = - 4 - 1

=> - 10x = - 5

=> x = 1/2

vậy_

b, đặt  \(A=\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^{99}}\)

\(3A=1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{98}}\)

\(3A-A=1-\frac{1}{3^{99}}\)

\(A=\frac{1-\frac{1}{3^{99}}}{2}\)

mk chỉ bt lm mấy phần hui à!

d)\(\frac{5}{17}+\frac{-4}{7}-\frac{20}{31}+\frac{12}{17}-\frac{11}{31}\)\(=\left(\frac{5}{17}+\frac{12}{17}\right)+\left(\frac{-20}{31}-\frac{11}{31}\right)+\frac{-4}{7}\)

\(=\frac{17}{17}+\frac{-31}{31}+\frac{-4}{7}\)\(=1+\left(-1\right)+\frac{-4}{7}\)\(=0+\frac{-4}{7}\)\(=-\frac{4}{7}\)

e)\(\frac{155-\frac{10}{7}-\frac{5}{11}+\frac{5}{23}}{403-\frac{20}{7}-\frac{13}{3}+\frac{13}{23}}\)

mk xl,mk ko bt lm các phần còn lại!

a,b you cứ tính bt nhé

c)\(\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}+\frac{1}{110}\)

\(=\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}+\frac{1}{10.11}\)

\(=\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}+\frac{1}{10}-\frac{1}{11}\)

\(=\frac{1}{4}-\frac{1}{11}\)

\(=\frac{7}{44}\)

d) \(\frac{5^2}{1.6}+\frac{5^2}{6.11}+\frac{5^2}{11.16}+\frac{5^2}{16.21}+\frac{5^2}{21.26}+\frac{5^2}{26.31}\)

\(=5\left(\frac{5}{1.6}+\frac{5}{6.11}+\frac{5}{11.16}+\frac{5}{16.21}+\frac{5}{21.26}+\frac{5}{26.31}\right)\)

\(=5\left(1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+\frac{1}{21}-\frac{1}{26}+\frac{1}{26}-\frac{1}{31}\right)\)

\(=5\left(1-\frac{1}{31}\right)\)

\(=5.\frac{30}{31}\)

\(=\frac{150}{31}\)